Defamation cases have rocketed since Aung San Suu Kyi's civilian government came to power in Myanmar, a report said Monday, as the rich and powerful intensify their use of draconian laws to muzzle civil society and the media.

There had been high hopes that the new government would herald a breakthrough for freedom of speech after half a century of stifling military rule.But the rights group Free Expression Myanmar (FEM) said those hoped-for gains were so far strikingly absent.

Ninety-seven cases have been brought under the notorious Article 66(d) of the Telecommunications Act since March 2016 compared with just 11 under the previous military-backed government, FEM said in a report.

Nearly all of them involve defamation charges covered by the law, the report said, snaring online satirists, activists and journalists.

Every case that has made it to court has ended with a guilty verdict and a prison sentence.

"Over the past two years, Article 66(d) has been the tool of choice for those in positions of power, who want to extend their punishment of people who are trying to hold them accountable, online," FEM said.

Amendments to the law prodded by public discontent have had "no discernible impact," it added.

The group reiterated calls for the "fundamentally undemocratic" law to be completely repealed, saying at least two-thirds of complaints would have been rejected had defamation been properly defined.

A recent case against the editor of the Myanmar Now news agency is still ongoing.

Swe Win stands charged with insulting a Buddhist monk who praised the killer of a Muslim government lawyer.

There have been only three appeals in the past two years as convicts under the law fear failure will earn an even longer sentence, the rights group said.

One of FEM's researchers, Maung Saungkha, was a victim of the law under the previous government.

The young writer was arrested in 2015 for penning a satirical verse about having a tattoo of the former junta-installed president Thein Sein on his penis.

"The previous government used 66(d) to pursue people who criticised them and they just paved the way for the next government to follow," he told AFP.